Hedgehog-like structure, PVDF- carbon nanohorn hybrid membranes for improved removal of VOCs from water

The hybrid membranes based on polyvinylidene fluoride (support) and single walled carbon nanohorns SWCNH (outer layer), with the surface architecture inspired by nature, i.e. hedgehog-like and desert rose-like structures, were performed. To tune materials precisely, physicochemistry, wettability, surface charge, the SWCNH were pretreated by oxidation, ultrasonication, or both mentioned processes. The modification of membranes resulted in a significant improvement in wettability from 110 degrees for pristine to 165.3 SWCNH-us-0.50 (reduced critical surface tension 41.08 +/- 1.1 mN m(-1) for pristine to 23.3 +/- 1.2 mN m(-1) for SWCNH-us-0.50), enhanced transport-separation properties, comparing to pristine one. The membranes with variable contact angles from 19.2 to 165.3 degrees were produced, however, due to the unique construction, the membranes were suitable in membrane distillation implemented for the first time for hazardous volatile organic compounds (VOCs) removal from water. All membranes were selective to VOCs, i.e. ethanol and methyl acetate that was foreseen by Hansen's Solubility Parameters. The substantial improvement in membrane performance was noticed when the oxidation or the ultrasonication pretreatment of modifiers was introduced. Permeate flux increased from 3.9 for pristine mem-brane to 12.3 kg m(-2) h(-1) for modified one. Simultaneously, process separation index (PSI) augmented from 3.1 to 32.2 kg m(-2) h(-1).

Automated summary

This study developed hybrid membranes based on polyvinylidene fluoride and single-walled carbon nanohorns, with surface structures inspired by hedgehogs and desert roses. Oxidation and ultrasonication treatments significantly improved the membrane performance, enhancing its selectivity and separation efficiency for volatile organic compounds. The modified membranes showed a wide range of contact angles and were suitable for membrane distillation.